Reflective structure for optical touch sensing

ABSTRACT

A reflective structure for optical touch sensing, which includes a transparent substrate, a plurality of microstructures and a transmittive reflective layer. The transparent substrate has a surface. The microstructures are disposed on the transparent substrate and expose a portion of the surface to allow a visible light to pass through. The transmittive reflective layer is disposed on the microstructures and at least covers a portion of the microstructures.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan applicationserial no. 102143498, filed on Nov. 28, 2013. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates a reflective structure, and more particularly, toa reflective structure for optical touch sensing.

2. Description of Related Art

In conventional art, an optical touch sensing structure is usuallycomposed of a light color paper base material and a plurality of blackink patterns printed on the light color paper base material. When aninfrared light emitted by a light pen is irradiated on the optical touchsensing structure, the black ink patterns may absorb the infrared light,and the light color paper base material may reflect and scatter theinfrared light. The infrared light being reflected or scattered may thenbe detected by an infrared light camera disposed in the light pen,thereby forming an infrared light image corresponding to the black inkpatterns. When the light pen contacts the optical touch sensingstructure and moves across a surface of the optical touch sensingstructure, a processor may determine positions of a contact point andmovements of the touch point according to a variation of the infraredlight image captured by the infrared light camera.

Since the light color paper base material includes a rough surface, theinfrared light generated by the light pen may be reflected and scatteredtowards multiple directions, thus the infrared light camera is prone tocapture a reflected image. In other words, signals regarding thepositions of the touch point may still be read even when the light penis tilted at an overly huge angle. However, the light color paper basematerial itself is not transparent (i.e. it is not light-transmittable),thus such optical touch sensing structure cannot be widely used incommon display. Further, even if a light-transmittable effect isaccomplished by using an extra thin light color paper base material, inaddition to reflect and scatter the infrared light, the light colorpaper base material may also reflect and scatter light emitted by thedisplay and environmental light, which causes the image to get foggy,thereby further reducing the image contrast and resolution.

SUMMARY OF THE INVENTION

The invention is directed to a reflective structure for optical touchsensing, capable of reflecting the infrared light through a transmittivereflective layer at least covering a portion of microstructures.Meanwhile, the transmittive reflective layer includes a nature of lighttransmittance for replacing above-said paper base material. Furthermore,the existing black ink patterns may be replaced if the transmittivereflective layer is patterned, such that the invention may directlyprovide an optical touch sensing structure without using the black inkpatterns.

The invention provides a reflective structure for optical touch sensing,which includes a transparent substrate, a plurality of microstructuresand a transmittive reflective layer. The transparent substrate has asurface. The microstructures are disposed on the transparent substrate,and the microstructures expose a portion of the surface to allow avisible light to pass through, so that overall light transmittance ofthe visible light of the reflective structure for optical touch sensingmay be improved. The transmittive reflective layer is disposed on themicrostructures and at least covers a portion of the microstructures.When an infrared light is incident to the microstructures, the portionof the microstructures may reflect the infrared light through thetransmittive reflective layer. Since the transmittive reflective layeris extra thin, the visible light is able to partially pass through, andthe overall light transmittance of the visible light of the reflectivestructure for optical touch sensing may also be improved.

In an embodiment of the invention, a refractive index of themicrostructures is identical or similar to a refractive index of thetransparent substrate.

In an embodiment of the invention, the microstructures and thetransparent substrate are integrally formed.

In an embodiment of the invention, a shape of an orthographic projectionof each of the microstructures on the substrate includes a circularshape, an elliptical shape, or a polygonal shape.

In an embodiment of the invention, the microstructures are disposed onthe surface of the transparent substrate, the microstructures arearranged in an array or a non-array, and a graphic formed by the arraycomprises a circular shape or a polygonal shape.

In an embodiment of the invention, the microstructures are relativelyrecessed to the surface of the transparent substrate, themicrostructures are arranged in an array or a non-array, and a graphicformed by the array comprises a circular shape or a polygonal shape.

In an embodiment of the invention, a thickness of the transmittivereflective layer is less than or equal to 40 nanometers.

In an embodiment of the invention, the transmittive reflective layercompletely covers surfaces of the microstructures.

In an embodiment of the invention, when an infrared light is incident toa portion of the microstructures covered by the transmittive reflectivelayer, the portion of the microstructures reflects the infrared lightthrough the transmittive reflective layer.

In an embodiment of the invention, when the infrared light is incidentto another portion of the microstructures not covered by thetransmittive reflective layer, the portion of the microstructuresscatters the infrared light.

In an embodiment of the invention, the transmittive reflective layer isa single-layer reflective layer or a multi-layer reflective layer.

In an embodiment of the invention, the reflective structure for opticaltouch sensing further includes a transparent protective layer coveringthe portion of the surface of the transparent substrate exposed by themicrostructures, the microstructures, and the transmittive reflectivelayer.

In an embodiment of the invention, a refractive index of the transparentprotective layer is between a refractive index of air and a refractiveindex of the transmittive reflective layer.

In an embodiment of the invention, the reflective structure for opticaltouch sensing further includes a plurality of optical absorptionportions disposed on the transparent protective layer and exposing aportion of the transparent protective layer.

In an embodiment of the invention, a width of each of themicrostructures is between 10 μm to 100 μm.

In an embodiment of the invention, a height of each of themicrostructures is between 5 μm to 50 μm.

Based on above, the reflective structure for optical touch sensing ofthe invention includes the transparent substrate, the microstructuresand the transmittive reflective layer. Accordingly, when the infraredlight emitted by the touch sensing element (i.e., the optical stylus)emits is irradiated on the reflective structure for optical touchsensing, the surface of the transparent substrate exposed by themicrostructures may allow the visible light to pass through, and themicrostructures covered by the transmittive reflective layer may reflectthe infrared light through the transmittive reflective layer to theinfrared light camera in the touch sensing element, so that thepositions of the touch point may be deduced. Moreover, when thereflective structure for optical touch sensing is subsequently installedin, for example, a common display (e.g., a liquid-crystal display, acathode ray tube display or a plasma display), the transparent substratethereof may be configured to allow most of light from the display topass through, and prevent the image from getting foggy. Therefore, thereflective structure for optical touch sensing of the invention mayinclude a wider range of application.

To make the above features and advantages of the disclosure morecomprehensible, several embodiments accompanied with drawings aredescribed in detail as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure, and are incorporated in and constitutea part of this specification. The drawings illustrate embodiments of thedisclosure and, together with the description, serve to explain theprinciples of the invention.

FIG. 1A is a schematic sectional view of a reflective structure foroptical touch sensing according to an embodiment of the invention.

FIG. 1B to FIG. 1E are partial top views illustrating microstructures ofthe reflective structure for optical touch sensing depicted in FIG. 1A.

FIG. 2 is a schematic sectional view of a reflective structure foroptical touch sensing according to another embodiment of the invention.

FIG. 3 is a schematic sectional view of a reflective structure foroptical touch sensing according to another embodiment of the invention.

FIG. 4A is a schematic sectional view of a reflective structure foroptical touch sensing according to another embodiment of the invention.

FIG. 4B is a schematic 3D diagram of one single microstructure of thereflective structure for optical touch sensing depicted in FIG. 4A.

FIG. 5 is a schematic sectional view of an optical touch sensingstructure composed of a reflective structure for optical touch sensingof the invention together with optical absorption portions.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1A is a schematic sectional view of a reflective structure foroptical touch sensing according to an embodiment of the invention. FIG.1B to FIG. 1E are partial top views illustrating microstructures of thereflective structure for optical touch sensing depicted in FIG. 1A.Referring to FIG. 1A, in the present embodiment, a reflective structurefor optical touch sensing 100 a includes a transparent substrate 110, aplurality of microstructures 120 a and a transmittive reflective layer130 a. The transparent substrate 110 has a surface 112. Themicrostructures 120 a are disposed on the transparent substrate 110, andthe microstructures 120 a expose a portion of the surface 112 to allow avisible light L1 to pass through. The transmittive reflective layer 130a is disposed on the microstructures 120 a and at least covers a portionof the microstructures 120 a. When an infrared light L2 is incident tothe microstructures 120 a, the portion of the microstructures 120 a mayreflect the infrared light L2 through the transmittive reflective layer130 a into a reflected infrared light L3. Practically, since theincident infrared light L2 is a light beam having a width and themicrostructures 120 a includes characteristics of geometrical shapes,the reflected infrared light L3 may be reflected towards multipledirections. Therefore, although it is not clearly illustrated in FIG.1A, a portion of the reflected infrared light L3 is reflected towards toan incidence direction of the infrared light L2, thereby creating areturning reflective effect. Therefore, when the infrared light camera(not illustrated) is disposed next to the an infrared light source (notillustrated), it works the same as common light pens, such that even ifthe incidence direction of the infrared light L2 is changed, theinfrared light camera may still capture the reflected infrared light L3.In other words, regardless of whether the light pen is vertical to thetransparent substrate 110 or is tilted at an overly huge angle, areflective image of the infrared light may still be captured.

More specifically, a material of the transparent substrate 110 of thepresent embodiment is, for example, a glass, a plastic, apolymethylmethacrylate (PMMA), or other materials with high lighttransmittance. More preferably, the microstructures 120 a and thetransparent substrate 110 are seamlessly connected. Namely, themicrostructures 120 a and the transparent substrate 110 are integrallyformed, and a refractive index of the microstructures 120 a is identicalto a refractive index of the transparent substrate 110. Of course, inother embodiments not illustrated, the microstructures 120 a and thetransparent substrate 110 may also be two structures separated from eachother, but the refractive index of the microstructures 120 a must beidentical or similar to the refractive index of the transparentsubstrate 110. Said embodiment still belongs to a technical meansadoptable in the present invention and falls within the protection scopeof the invention. Herein, as shown in FIG. 1A, in view of the sectionalview, the microstructures 120 a of the present embodiment are of arcshapes.

More specifically, referring to FIG. 1B, a shape of an orthographicprojection of each of microstructures 120 a 1 on the transparentsubstrate 110 is a polygonal shape, such as a hexagon; or, referring toFIG. 1C, a shape of an orthographic projection of each of themicrostructures 120 a 2 on the transparent substrate 110 is a regularhexagon; or, referring to FIG. 1D, a shape of an orthographic projectionof each of the microstructures 120 a 3 on the transparent substrate 110is a circular shape; or, referring to FIG. 1E, a shape of anorthographic projection of each of the microstructures 120 a 4 on thetransparent substrate 110 is an elliptical shape, or other appropriateshapes.

The shapes of orthographic projections of the microstructures 120 a 1 to120 a 4 on the transparent substrate 110 belong to a technical meansadoptable in the present invention and falls within the protection scopeof the invention. Generally, a width of conventional black ink patternsis substantially 100 μm. Accordingly, it is more preferable that each ofthe microstructures 120 a as a replacement to the conventional black inkpatterns includes a width no more 100 μm, so as to avoid an excessiveoptical scattering phenomenon. Further, it is also more preferable thateach of the microstructures 120 a includes an aspect ratio which is notoverly big, so as to facilitate in manufacturing the transmittivereflective layer 130 a while avoiding the excessive optical scatteringphenomenon. Herein, the aspect ratio of each of the microstructures 120a is set to no more than ½. More preferably, a width W of each of themicrostructures 120 a is between 10 μm to 100 μm, and a height H of eachof the microstructures 120 a is between 5 μm and μm 50 μm.

As shown in FIG. 1A, the microstructures 120 a are disposed on thesurface 112 of the transparent substrate 110. Herein, the surface 112 ofthe transparent substrate 110 is substantially a flat surface. Themicrostructures 120 a are arranged in an array or a non-array, andexpose said flat surface (i.e., the surface 112). Therein, in case theyare arranged in the array, a graphic formed by the array may be, forexample, a circular shape or a polygonal shape, but the invention is notlimited thereto. The transmittive reflective layer 130 a completelycovers surfaces of the microstructures 120 a, thus when the infraredlight L2 is incident to the microstructures 120 a, the microstructures120 a may reflect the infrared light L2 (i.e., the infrared light L3 inFIG. 1A) through the transmittive reflective layer 130 a coveredthereon. More preferably, a thickness of the transmittive reflectivelayer 130 a is less than or equal to 40 nanometers, so that a capabilityof reflecting the infrared light L2 may also be provided in addition toa capability of light transmittance. It should be noted that, althoughthe transmittive reflective layer 130 a illustrated in FIG. 1A issubstantially a single-layer reflective layer, but the transmittivereflective layer may also be a multi-layer in other embodiments notillustrated. Said embodiment still belongs to a technical meansadoptable in the present invention and falls within the protection scopeof the invention.

Further, a reflective structure for optical touch sensing 100 a mayfurther includes a transparent protective layer 140, and the transparentprotective layer 140 covers the portion of the surface 112 of thetransparent substrate 110 exposed by the microstructures 120 a, themicrostructures 120 a, and the transmittive reflective layer 130 a. Morepreferably, a refractive index of the transparent protective layer 140is between a refractive index of air and a refractive index of thetransmittive reflective layer 130 a (e.g., the refractive index isbetween 1 and 2), so that overall light transmittance of the visiblelight L1 of the reflective structure for optical touch sensing 100 a maybe improved.

In the present embodiment, the surfaces of microstructures 120 adisposed on the transparent substrate 110 are completely covered by thetransmittive reflective layer 130 a, and the transmittive reflectivelayer 130 a has a strong effect in reflecting the infrared light L2,while the transparent substrate 110 has a weaker effect in reflectingthe infrared light L2. Therefore, when the infrared light L2 emitted bya touch sensing element (e.g., an optical stylus, not illustrated) isirradiated on the reflective structure for optical touch sensing 100 a,the surface 112 of the transparent substrate 110 exposed by themicrostructures 120 a may allow the visible light L1 to pass through.The microstructures 120 a covered by the transmittive reflective layer130 a may reflect the infrared light L2 through the transmittivereflective layer 130 a to the infrared light camera in the touch sensingelement for replacing an infrared light reflection function originallyincluded by a light color paper base material. The visible light L1 maydirectly pass through the transparent protective layer 140 and thetransparent substrate 110. Therefore, when the reflective structure foroptical touch sensing 100 a is installed in, for example, a display (notillustrated), in addition to serve as an effective reflector for theinfrared light L2, the transparent substrate 110 thereof may beconfigured to effectively sustain the light transmittance of the displayand reduce the image from getting foggy. Therefore, the reflectivestructure for optical touch sensing 100 a of the present embodiment mayinclude a wider range of application.

It should be noted that the reference numerals and a part of thecontents in the previous embodiment are used in the followingembodiments, in which identical reference numerals indicate identical orsimilar components, and repeated description of the same technicalcontents is omitted. For a detailed description of the omitted parts,reference can be found in the previous embodiment, and no repeateddescription is contained in the following embodiments.

FIG. 2 is a schematic sectional view of a reflective structure foroptical touch sensing according to another embodiment of the invention.Referring to FIG. 2, a reflective structure for optical touch sensing100 b of the present embodiment is similar to the reflective structurefor optical touch sensing 100 a of FIG. 1A, and a major differencebetween the two is that: in the present embodiment, microstructures 120b are not completed covered by a transmittive reflective layer 130 b ofthe reflective structure for optical touch sensing 100 b, and themicrostructures 120 b disposed on the surface 112 of the transparentsubstrate 110 are arranged in an array and expose a portion of thesurface 112. More specifically, a transmittive reflective layer 130 bonly directly covers a portion of the microstructures 130 b and thesurface 112 of the transparent substrate 110 between the microstructures120 b covered by the transmittive reflective layer 130 b. In otherwords, the transmittive reflective layer 130 b exposes another portionof the microstructures 120 b. Therefore, when the infrared light L2 isincident to the microstructures 120 b, the portion of themicrostructures 120 b covered by the transmittive reflective layer 130 bmay reflect the infrared light L2 (the infrared light L3 in FIG. 2)through the transmittive reflective layer 130 b, and another portion ofthe microstructures 120 b not covered by the transmittive reflectivelayer 130 b may scatter the infrared light L2 (i.e., an infrared lightL4 in FIG. 2).

The transmittive reflective layer 130 b of the present embodiment may bereferred to as a patterned transmittive reflective layer capable ofreplacing the conventional black ink patterns and forming infrared lightreflective patterns. Accordingly, the reflective structure for opticaltouch sensing 100 b may directly become an optical touch sensingstructure without using the black ink patterns, so that overall visiblelight transmittance may also be improved.

FIG. 3 is a schematic sectional view of a reflective structure foroptical touch sensing according to another embodiment of the invention.Referring to FIG. 3, a reflective structure for optical touch sensing100 c of the present embodiment is similar to the reflective structurefor optical touch sensing 100 b of FIG. 2, and a major differencebetween the two is that: in the present embodiment, a transmittivereflective layer 130 c of the reflective structure for optical touchsensing 100 c is composed of a plurality of transmittive reflectivepatterns 132 c, and the transmittive reflective patterns 132 c arerespectively disposed on the microstructures 120 b without connecting toone another. As shown in FIG. 3, the transmittive reflective patterns132 c are located on arc-shaped top surfaces of the microstructures 120b.

FIG. 4A is a schematic sectional view of a reflective structure foroptical touch sensing according to another embodiment of the invention.FIG. 4B is a schematic 3D diagram of one single microstructure of thereflective structure for optical touch sensing depicted in FIG. 4A.Referring to FIG. 4A, a reflective structure for optical touch sensing100 d of the present embodiment is similar to the reflective structurefor optical touch sensing 100 c of FIG. 3, and a major differencebetween the two is that: in the present embodiment, microstructures 120d of the reflective structure for optical touch sensing 100 d arerelatively recessed to the surface 112 of the transparent substrate 110,and the microstructures 120 d are arranged in an array or a non-arrayand expose a portion of the surface 112. Therein, in case they arearranged in the array, a graphic formed by the array may be, forexample, a circular shape or a polygonal shape, but the invention is notlimited thereto. Transmittive reflective patterns 132 d of thetransmittive reflective layer 130 d are respectively disposed on themicrostructures 120 d without connecting to one another. As shown inFIG. 4A, the transmittive reflective patterns 132 d are located onarc-shaped recess surfaces of the microstructures 120 d.

More specifically, referring to FIG. 4B, each of the microstructures 120d is a depressed corner cube which is a structure composed of threeplanes perpendicular to one another, so that an incident light ray R maybe reflected for three times before going back in their originaldirections thereby creating the returning reflective effect. Therefore,when the infrared light camera (not illustrated) is disposed next to thean infrared light source (not illustrated), it works the same as commonlight pens, such that even if the incidence direction of the infraredlight (the infrared light L2 in FIG. 2) is changed, the infrared lightcamera may still capture the reflected infrared light (the infraredlight L3 in FIG. 2). In other words, regardless of whether the light penis vertical to the transparent substrate 110 or is tilted at an overlyhuge angle, a reflective image of the infrared light may still becaptured.

FIG. 5 is a schematic sectional view of a reflective structure foroptical touch sensing according to another embodiment of the invention.Referring to FIG. 5, a reflective structure for optical touch sensing100 e of the present embodiment is similar to the reflective structurefor optical touch sensing 100 a of FIG. 1A, and a major differencebetween the two is that: in the present embodiment, the reflectivestructure for optical touch sensing 100 e further includes a pluralityof optical absorption portions 150, and the optical absorption portions150 are disposed on the transparent protective layer 140 and exposes aportion of the transparent protective layer 140. Herein, the opticalabsorption portions 150 may be referred to as dark spots not reflectingthe visible light and the infrared light, and a material thereof is, forexample, a black ink. However, the invention is not limited thereto.When the infrared light L2 emitted by the touch sensing element (e.g.,the optical stylus, not illustrated) is irradiated on the reflectivestructure for optical touch sensing 100 e, the visible light L1 and theinfrared light L2 may both be absorbed by the optical absorptionportions 150, such that the infrared light L2 may create a relativelygreater difference in the reflective indexes on the reflective structurefor optical touch sensing 100 e. Accordingly, when the reflectivestructure for optical touch sensing 100 e is subsequently installed in,for example, a display (not illustrated), in addition to serve as aneffective reflector for the infrared light L2, the light transmittanceof the display may be effectively sustained and the image from gettingfoggy may also be reduced. Therefore, the reflective structure foroptical touch sensing 100 e of the present embodiment may include awider range of application.

In summary, the reflective structure for optical touch sensing of theinvention includes the transparent substrate, the microstructures andthe transmittive reflective layer. Accordingly, when the infrared lightemitted by the touch sensing element (i.e., the optical stylus) emits isirradiated on the reflective structure for optical touch sensing, thesurface of the transparent substrate exposed by the microstructures mayallow the visible light to pass through, and the microstructures coveredby the transmittive reflective layer may reflect the infrared lightthrough the transmittive reflective layer to the infrared light camerain the touch sensing element, so that the positions of the touch pointmay be deduced. Moreover, when the reflective structure for opticaltouch sensing is subsequently installed in, for example, a commondisplay (e.g, a liquid-crystal display, a cathode ray tube display or aplasma display), the transparent substrate thereof may be configured toallow most of light from the display to pass through, and prevent theimage from getting foggy. Therefore, the reflective structure foroptical touch sensing of the invention may include a wider range ofapplication.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the structure of the presentdisclosure without departing from the scope or spirit of the disclosure.In view of the foregoing, it is intended that the present disclosurecover modifications and variations of this disclosure provided they fallwithin the scope of the following claims and their equivalents.

What is claimed is:
 1. A reflective structure for optical touch sensing,comprising: a transparent substrate having a surface; a plurality ofmicrostructures disposed on the transparent substrate, wherein themicrostructures expose a portion of the surface to allow a visible lightto pass through; and a transmittive reflective layer disposed on themicrostructures and at least covering a portion of the microstructures.2. The reflective structure for optical touch sensing as recited inclaim 1, wherein a refractive index of the microstructures is identicalor similar to a refractive index of the transparent substrate.
 3. Thereflective structure for optical touch sensing as recited in claim 1,wherein the microstructures and the transparent substrate are integrallyformed.
 4. The reflective structure for optical touch sensing as recitedin claim 1, wherein a shape of an orthographic projection of each of themicrostructures on the substrate comprises a circular shape, anelliptical shape, or a polygonal shape.
 5. The reflective structure foroptical touch sensing as recited in claim 1, wherein the microstructuresare disposed on the surface of the transparent substrate, themicrostructures are arranged in an array or a non-array, and a graphicformed by the array comprises a circular shape or a polygonal shape. 6.The reflective structure for optical touch sensing as recited in claim1, wherein the microstructures are relatively recessed to the surface ofthe transparent substrate, the microstructures are arranged in an arrayor a non-array, and a graphic formed by the array comprises a circularshape or a polygonal shape.
 7. The reflective structure for opticaltouch sensing as recited in claim 1, wherein a thickness of thetransmittive reflective layer is less than or equal to 40 nanometers. 8.The reflective structure for optical touch sensing as recited in claim1, wherein the transmittive reflective layer completely covers surfacesof the micro structures.
 9. The reflective structure for optical touchsensing as recited in claim 1, wherein when an infrared light isincident to a portion of the microstructures covered by the transmittivereflective layer, the portion of the microstructures reflects theinfrared light through the transmittive reflective layer.
 10. Thereflective structure for optical touch sensing as recited in claim 9,wherein when the infrared light is incident to another portion of themicrostructures not covered by the transmittive reflective layer, theanother portion of the microstructures scatters the infrared light. 11.The reflective structure for optical touch sensing as recited in claim1, wherein the transmittive reflective layer is a single-layerreflective layer or a multi-layer reflective layer.
 12. The reflectivestructure for optical touch sensing of claim 1, further comprising: atransparent protective layer covering the portion of the surface of thetransparent substrate exposed by the microstructures, themicrostructures, and the transmittive reflective layer.
 13. Thereflective structure for optical touch sensing as recited in claim 12,wherein a refractive index of the transparent protective layer isbetween a refractive index of air and a refractive index of thetransmittive reflective layer.
 14. The reflective structure for opticaltouch sensing as recited in claim 12, further comprising: a plurality ofoptical absorption portions disposed on the transparent protective layerand exposing a portion of the transparent protective layer.
 15. Thereflective structure for optical touch sensing as recited in claim 1,wherein a width of each of the microstructures is between 10 μm to 100μm.
 16. The reflective structure for optical touch sensing as recited inclaim 1, wherein a height of each of the microstructures is between 5 μmto 50 μm.